Thin wall plastic tubing is often used for over-wrapping product containers, for example bottles containing personal hygiene, pharmaceutical or food products. In one form, the plastic tubing is applied as a label over a major portion of the container to identify the product and/or enhance the appearance of the container. In another form, the plastic tubing provides a tamper-evident band that covers the container cap and neck, serving to indicate whether the container has been opened prior to purchase. Identifying labels and tamper-evident bands are referred to collectively herein as tubular labels. In many cases the plastic tubing is processed so as to be shrinkable by the application of heat after a cut length of tubing has been placed over the container causing the tubing to conform snugly to the contours of the container.
The subject plastic tubular labels are applied to product containers in manufacturing environments, therefore process reliability, tubing length consistency, and neatness of the cut edge are important factors. Most known machines for the application of thin wall plastic tubing to containers employ a scissor-type double blade cutter or a guillotine-type single blade cutter. Another cutter type operates a number of rotatably mounted blades that are positioned around a central hole through which a tubular film is passed. The blades are caused to rotate after the film has been advanced a predetermined length.
One such cutter is described in U.S. Pat. No. 5,531,858 entitled “Shrinkable Label Inserting Machine” in which the blades are mounted on a number of rotatable wheels that are in contact with a single driven band, e.g. a belt or chain, that drives all of the wheels.
A second such cutter is described in U.S. Pat. No. 5,791,220 entitled “Cutting Device Of Packing Apparatus” in which the blades are mounted on a number of rotatable wheels that are in contact with one of a series of bands that drive each wheel in tandem.
A third such cutter is described in U.S. Pat. No. 5,970,685 entitled “Cutting Mechanism For A Thermal Shrinking Film Labeling Machine” in which the blades are mounted on a number of electronic or hydraulic rotary tool holders that are adapted for rotating back and forth.
The present invention provides a unique film tubing cutter that employs a driving mechanism not disclosed in any known prior art and is described below.
The present invention cutter may also be used for cutting lengths of thin wall tubing that is formed substantially continuously by the process of extrusion. The resulting extruded tubing product is cut to defined lengths for packaging and shipping. The present invention is useful to cut lengths of tubing emerging from the extruding operation or subsequently in substitution for the current single blade cutting that is commonly used.